Well, I must admit I considered Quake ugly and not very impressive at the time it was released ten years ago. At this time, pseudo-3D games like Duke Nukem were much prettier and more fun to play.
However, some years ago, I played the original Quake a little bit again since after the source code was released, some guys tried to rewrite the Quake engine to look a little like Doom3 (dynamic shadows, bump mapping and so on).
At the time, it was very slow and due to the pretty bad models and textures didn't really look as impressive as it could. Also, unfortunately, the project seems to be dead now. But you might still give it a try:
http://tenebrae.sourceforge.net/